[gmx-users] g_mindist error "Cannot open file with NULL filename string"

[ABEL Stephane]

Hi All,

I would like to use g_mindist (vGMX2018.2) to compute the number of total contacts between each residue of a protein and surfactant molecules. For this I use the following command

 gmx_mpi mindist -f myXTC.xtc -s MYPDB.pdb -n MYNDX.ndx -b 200000 -e 215000 -dt 4 -d 0.4 -respertime -printresname -group -od  Protein_AlkylChain_Contact_min_res.xvg -on Protein_AlkylChain_Contact_Number.xvg < Protein_AlkylChain.txt


 I obtain the following fatal error, Why ?

 -------------------------------------------------------
Program:     gmx mindist, version 2018.2
Source file: src/gromacs/fileio/gmxfio.cpp (line 345)

Fatal error:
Cannot open file with NULL filename string

For more information and tips for troubleshooting, please check the GROMACS
website at http://www.gromacs.org/Documentation/Errors
-------------------------------------------------------

Please note I also would like that each contact between each residue and surfactant atoms is counted as one. Is this possible with the command above ?

Thanks for you help,

Stéphane